Pneumatic power tools have been used extensively in industrial and construction applications for well over the last century. These tools frequently are pneumatic grinders, drills and wrenches in industrial applications and paving breakers, earth borers and chipping hammers in the construction industry.
All these tools, however, have the same basic configuration, including a reciprocating piston or rotary air motor for driving or impacting an associated tool and a handle portion with an operator-controlled trigger and valve assembly that connects compressed air from a fitting to the motor. Fluid passageways are conventionally formed in the handle portion and in a tool body portion that is adjacent to the motor for conveying air under pressure to the motor.
The formation of the air passages in the handle portion and in the tool body has always been a problem because it is not economically practical to core these passageways during the forging operations for the handle and the tool body, particularly where these fluid passageways must be curved to accommodate the configuration of the tool. For these reasons, the fluid passageways in the handle portion and the tool body are today formed largely by drilling operations subsequent to the forging of the parts. Where the passageways must curve or turn, it is necessary to drill multiple angularly related intersecting bores in the tool and then cap the exterior openings of the bores with a weldment to seal the passageway. This multiple drilling technique requires different machine setups because of their angular relationship and has been found to be a very significant cost factor in the overall tool cost.
It is a primary object of the present invention to ameliorate the problems noted above in forming fluid passageways in pneumatic power tools.